Drink driving limits

280 people were killed in drink driving accidents in the UK in 2012. While this is down over 75% since 1979, alcohol has become more readily available and in more drinkable forms such as RTDs (ready-to-drink) and alcopops.

How do I calculate my blood alcohol level?

The other problem is that it’s difficult to judge whether you are over the limit or not. It is impossible to calculate your blood alcohol level because it depends on so many different factors:

Your gender: a man of the same weight as a woman will be able to drink more before the blood alcohol concentration is the same

The amount you’ve eaten, and how recently you’ve eaten: eating a large meal just before drinking will slow the absorption of alcohol; drinking on an empty stomach will mean a fast absorption of alcohol

Your liver’s ability to process alcohol – if your liver is damaged, it will take longer

The type of drinks you are drinking, and how much: beer has a low alcohol content compared to spirits, so a mouthful of beer is much different to a mouthful of vodka which could be over 40% proof.

Your metabolism: a healthy body will process alcohol at around one standard drink per hour; an unhealthy body will take longer

Your stress and tiredness levels: higher stress and tiredness will lead to higher blood alcohol concentrations as your body can’t process the alcohol as effectively.

What’s a safe level of alcohol to drive with?

Any amount of alcohol will have some negative effect on your driving. Even if you don’t feel drunk, your reactions are affected. It’s best to take public transport, get a friend or relative to drive you, or just don’t drink. There are zero-alcohol beers, mocktails and soft drinks and you don’t have to drink to have fun. Not every night needs to end up at a pub, club or bar – there are hundreds of options to do cool stuff without drinking.

Bear in mind that if you have drunk heavily then you will almost certainly be over the limit the next morning. Many drivers booked for drink driving are caught the following day. It’s quite easy to accumulate 12-15 units in a night of heavy drinking, and that means 12-15 hours processing time, at minimum. If you stop drinking at 2am, you’ll still have alcohol in your system mid-to-late afternoon the following day!

When should I stop drinking, then?

Obviously to be completely safe you wouldn’t have any alcohol at all. To be sure you are under the limit the following morning, stop drinking early (say, 10pm), ensure you have eaten, only have a maximum of a couple units of alcohol and leave a good 10 hours before you drive again.

2 units of alcohol is either one pint of regular beer, one glass of wine, two small alcopops, two single measures of spirits or half a pint of cider.

How can I speed up alcohol elimination from my body?

Many people think that just because they’ve been to sleep that alcohol from the day before will be gone. This isn’t the case. You will process alcohol at the same rate whether you are asleep or awake. For a healthy males, you will process around one unit per hour, but this can vary.

Your liver does the most work, but you do sweat and breathe minute amounts out of your body. However, this doesn’t mean you should take a sauna; it will make negligible difference.

Black coffee, water and eating after you are drunk will not speed up the process of elimination. Water will reduce the effects of a hangover by ensuring you are not dehydrated.

What about taking drugs?

Some drugs will slow down your body’s elimination of alcohol. Cocaine, for example, binds to alcohol and keeps both the cocaine and alcohol in your system longer.

How does alcohol affect your driving?

Alcohol slows your reaction times and prevents you from processing information as effectively. It makes it more difficult for the brain to receive signals from your eyes, and once you have managed to process what you need to do, getting instructions from your brain to your muscles is delayed.

Alcohol can cause double-vision which makes it difficult for you to judge where objects are when you are driving.

You may feel a heightened sense of self-confidence causing you to take risks that you wouldn’t usually take.

The Highway code says:

Rule 95

Do not drink and drive as it will seriously affect your judgement and abilities. You MUST NOT drive with a breath alcohol level higher than 35 microgrammes/100 millilitres of breath or a blood alcohol level of more than 80 milligrammes/100 millilitres of blood.

Alcohol will

give a false sense of confidence

reduce co-ordination and slow down reactions

affect judgement of speed, distance and risk

reduce your driving ability, even if you’re below the legal limit

take time to leave your body; you may be unfit to drive in the evening after drinking at lunchtime, or in the morning after drinking the previous evening

The best solution is not to drink at all when planning to drive because any amount of alcohol affects your ability to drive safely. If you are going to drink, arrange another means of transport.

Law RTA 1988 sects 4, 5 & 11(2)

What are the penalties if I get caught drink driving?

Being in charge of a vehicle while above the legal limit or unfit through drink

You may get:

3 months’ imprisonment

up to £2,500 fine

a possible driving ban

Driving or attempting to drive while above the legal limit or unfit through drink

You may get:

6 months’ imprisonment

up to £5,000 fine

a driving ban for at least 1 year (3 years if convicted twice in 10 years)

Refusing to provide a specimen of breath, blood or urine for analysis

You may get:

6 months’ imprisonment

up to £5,000 fine

a ban from driving for at least 1 year

Repeat offenders

If you get caught drink driving a second or subsequent time within a 10-year period, you’ll be banned at least three years.

Causing an accident while under the influence of alcohol

If you cause an accident which results in a fatality, the penalties are severe:

an unlimited fine

up to 14 years in prison

minimum 2-year disqualification

3-11 points

an extended test before you can get your licence back

Other problems you could face

A conviction for drink-driving also means:

your car insurance costs will increase significantly

if you drive for work, your employer will see your conviction on your licence